Inventory Control
DENNISS~E~ERS Central Community Hgh Schwi Roue 50 West Breese. IL 62230
An Inexpensive Device for Producing, Measuring, and Moving Gas Rlchard Wojl 1641 Hastings Ave. West Poll Townsend. WA 98368
Working with gases in a high school laboratory can be difficult because the equipment usually used is too expensive, fragile, and cumbersome to he practical. I have found a cheap and easy method that allows my students to conduct experiments with gases, using disposable plastic syringes and aquarium tubing. The gas is produced in a syringe (Fig. 1) by pulling the chemicals into the syringe through small plastic aquarium tubing that fits snugly over the intake nozzle of the syringe. The connections are held together by friction. For example, pull a Na2C03solution into one syringe and a weak HCl solution in a second syringe. Start the reaction by pressing the plunger, which will push one reaction mixture through the tubing and into the other syringe. Then release the plunger. The production of the COz pushes the reaction mixture back out of the syringe into the second. Tip up the syringe containing the gas, and hold i t above the second (Fig. 2). As the plunger is pressed, spent reagents and a small amount of gas travel through the tube to the second syringe, leaving relatively dry gas. If a drier gas is desired, the gas can be forced through a drying tube (Fig. 3) containing CaClz or another drying agent that has been purged with some of the generated gas. T o insure the safety of the reactions they are first conducted in an open beaker to find concentrations that give controllable reactions. They are subsequently tried in the syringes and adjustments are made in reagent concentration necessary to achieve reaction rates that produce the gas in 23 minutes.
1052
Journal of Chemical Education
8
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syringe
Figure 1. A syringe being used to produce Me gas. Figure 2. Two syringes in use to mix reactants and form me gas. Figure 3. A drying tube in use with the syringe.
